Method of making hollow panels



Sept. 25, 1945. Q Q DAVls 2,385,352

METHOD OF MAKING HOLLOW PANELS Filed June i2, 1942 INVENTOROA/VfPCLABE/VftDAV/j BY MM .2? m

ATTORNEY l atented Sept. 25, 1945 METHOD OF MAKING HOLLOW PANELS OliverClarence Davis, Louisville, Ky., assignor to The Mengel Company,Louisville, Ky., a corporation of New Jersey Application June 12, 1942,Serial No. 446,817

7 Claims.

This invention relates to methods and apparatus for making structuralunits such as doors, walls, partitions, or the like, and, inasmuch asthe invention may be utilized to great advantage in the making of doors,it will be illustrated and soft grid, a d for retaining the Said facingdescribed specifically with reference to such hers fiat during e glueSetting Operationstructural units. For a better understanding of theinvention,

In recent years, the demand for a door that reference s made to theaccompanying d w n is light in weight, thermal insulating, fire-resistin Which! ant, inexpensive to manufacture, structurally Figure 1 is aperspective View Of a (1001 made stable upon exposure to air of varyinghumidity, in accordance with the teachings of this i venand workable andstrong at its edge portions for ti w parts k n w y for cleerness ofreceiving conventional hardware such as latches, illustration; doorknobs, hinges, etc., has greatly increased. Figure 2 is a perspective vw on a n ar d Many structural arrangements have b e advoiii scale of thegrid or filler of the door with one cated, but the method of making thesame has of the ribs broken away to show the ventilating become a veryimportant consideration. Slots One very satisfactory structuralarrangement Figure 3 is an enlarged View Of & D f for a doorcontemplates the use of a grid or filler 0118 Of the ribs 0 t dillustrate e of relatively soft material surrounded by a framew Clearlythe Ventilating 510155 work of relatively firm material constituting theFigure 4 is a Side elevation f a multiple rails or edge portions of thedoor, with facing plate press havin a. plurality of the aforesaidmembers of wood Veneer or lywood panels, structural units lodged thereinfor processing;

Such a door is shownin United States Letters Figure 5 is an enlargedView, p y in Section, Patent No. 2,173,808, issued September 19, 1939, Wof the combination a ve nd connectinap u to G. D. Kellogg. employed toplace pressure within the structural In producing doors of this ty it ii bl assembly, and illustrating the pressure valve to employ alightweight thermal-insulating maclosed; terial for making the grid orfiller of the core, Figure 6 is an enlarged view, pa y in section. suchas fibre board of the kind frequently used 0f the combination valve andconnecting plug, for thermal insulation and weighing, for instance,illustrating the pressure valve open, and the con- 8 to 14 pounds to thecubic foot, and to employ nesting plug sealed in the aperture I5 of thea hot-setting glue for securing, in a short period aforesaid structuralassembly. of time, the facing members to the grid and While I have showna fabricated or built-up framework assembly. grid for the door, it is tobe understood thata To obtain a satisfactory bond between thefacmachined or molded grid, similar to that shown ing members, grid andframework, the aforesaid in Figures 3 and 4 of the aforesaid patent toparts are preferably assembled in a hot-plate G. D. Kellogg, may besubstituted without depress, and subjected to relatively high pressuresparting from the spirit of the invention. Simiand temperatures for atime suficient to set the larly, while I have omitted the incombustiblelue. sheets of asbestos placed between the grid and However, thepressure required to assemble facing members, it is to be understoodthat these such structural units often injures the soft grid may be usedwithout departing from the spirit or filler, and produces a door havingobjectionof my invention. able waves or similar imperfections on theouter With reference to Figure 1, it will be observed surface of thefacing members thereof. that the structural unit is illustrated in theform Therefore, the primary object of the present of a door having agrid, or lattice-work filler l6 invention is to provide a method ofmaking such of relatively soft material, a framework comprisdoors thatwill not only eliminate entirely the ing rails 24 and stiles 26 ofrelatively hard ma aforesaid objections, but'greatly increaseproducterial, and facing members [2, which members tion efiiciency.preferably consist of composite piles of wood ve- Briefiy, the methoddisclosed in the present neer, the grain of one ply 22 being arrangedcrossinvention comprises assembling the grid, framewise with respect tothe grain of the ply 2!. work, and facing members with a suitable glueor The grid 16 preferably consists of two series of other adhesiveinterposed between the parts; ap-

plying external heat and pressure to the parts to bond the sametogether; and simultaneously therewith applying pressure internally ofthe said assembly to prevent collapsing or injury to the intercrossedstrips [6a of fibrous or other relatively soft material, in which thestrips in a given series extend substantially parallel to each other andat an angle to the strips in the other of the said series. The strips ofeach series are preferably notched at I6b, as illustrated in Figures 2and 3, so that the strips interlock at the cross-over points between thestrips of the two series. Figure 1 clearly illustrates this.arrangement, and the enlarged detail of the grid I6 shown in Figure '2clearly shows the interlocked relation of the strips at the crossoverpoints. It is also to be understood that the notches Ifib may bealternately arranged along the opposite edges of the strips IBa, so thatthe grid will become an inseparable, interlocked-assembly, when thefacing members are secured thereto.

With further reference to Figures 1 and 2, it will be apparent that theinterlocked strips Ilia of the grid I6 form a plurality of compartments,which, when the facing members are secured thereto form a plurality ofclosed compartments. Therefore, to provide a communication between thevarious compartments, an auxiliary notch I60 is cut adjacent each notchIGb. Figures 2 and 3 particularly illustrate this construction, and itis to be understood that various other means may be employed to providethe required communication between the various chambers, such as holesin the faces of the strips I611.

Inorder to minimize twisting of the several strips along thelongitudinal axis thereof, the strips Ilia are made thick (broad) ontheir edges, and of relatively soft and lightweight material such as thefibre insulating board previously mentioned. Strips having a thicknessof one-half inch, or more, have been found to be satisfactory, and ithas been observed that strips of this thickness provide sufficientcontact area with the inside It is to be understood also that theabutting edges of the rails 24 and stiles 26 may be mortised ordove-tailed to provide additional mechanical strength for the frameworkwithout departing from the spirit of this invention. Likewise, it is tobe understood that the framework is preferably constructed of wood orother relatively hard material having the required proportions toaccommodate conventional hardware such as latches, door knobs, hinges,etc.

As illustrated in Figure l, the facing members I2 preferably consist ofcomposite plies of wood veneer having the grain of one crosswise withrespect to the grain of the ply 2|. A conventional water-resistantadhesive 23 secures the plies together, and, as well known in the art,such an adhesive may comprise a composition including, casein orphenol-aldehyde resin.

As indicated in Figures 1, 4, 5 and 6, the rail 24 is provided with anaperture I5 for receiving a connection to a fluid pressure such as steamor air.

With reference to Figure 5, it will be observed that the connectioncomprises a conduit I4, which conduit is connected to a suitable sourceof fluid pressure. A valve I I is interposed in the conduit I4, whichvalve is opened and closed by the handle I3. In Figure 5 the valve isillustrated in a ply 22 arranged a closed condition, while, in Figure 6,the valve is illustrated in open condition.

As further illustrated in Figure 5, the conduit I4 is enlarged at 6, anda sleeve 8 is slidably mounted thereon. A rubber sleeve I is disposedupon conduit I4 between the enlarged end 6 and slidable sleeve 8. It isto be observed that handle I3 is provided with cams I0, one on each sideof valve II, that engage the slidable sleeve 8, and that the cams IIIare constructed and arranged to move the sleeve 8, longitudinally alongthe conduit I4 and compress the rubber sleeve 1, when the valve I I ismoved to an open condition.

Thus, as illustrated in Figure 6, when the connector is inserted intothe aperture I5 in the door rail, and the valve handle I3 actuated toopen the valve, the rubber sleeve I is compressed, thereby sealing theconnection in the said aperture. Similarly, when the valve handle I3 isactuated to close the valve, the rubber sleeve 7 restores to its normalshape, as illustrated in Figure 5, thereby enabling the connector to beeasily withdrawn from the aperture IS.

A conventional hot-plate press is illustrated in Figure 4, which pressis shown loaded with a plurality of doors for processing. The numerals 23 and 26 designate the rails and stiles of the respective doors, and thenumeral I5 designates the aperture into which the pressure connector isinserted.

As illustrated in Figure 4, each door assembly is disposed betweenconventional heated-platens, which platens are connected, via suitableflexibleconnections, to asteam supply-line 25 for heating the respectiveplates. The top platen 21a is usually fixed to the upper cross-head 22of the press, while the intervening platens 2'! are slidably mountedbetween the tie-rods 2 I. The usual discharge pipes for the platens arenot shown, and it is to be understood that these are provided.

It is also to be understood that the press is provided with a suitablemeans for retaining the platens in open or spaced relation, when the ramI8 is lowered, which means is represented by rods I9 upon which theplatens rest when the ram I8 is lowered. The numeral 20 designates aconduit connection to a fluid pressure unit for actuating the ram l8.

In practicing the present invention the grids I6, rails 24, stiles 26and facing members I2 are assembled with the proper adhesive distributeduniformly and continuously between the abutting edges and surfaces ofthe various parts. The doors thus assembled are then loaded into aheated platen press, as illustrated in Figure 4.

A pressure connector is inserted into each rail aperture I5, and,substantially simultaneously with the application of external pressureto the door assemblies via ram I8, fluid pressure, preferably air, isapplied via each respective pressure connection into the interior ofeach door assembly. While not shown, it is to be understood that amaster valve may be associated with the fluid pressure connection fromconduits I4, which masing of the glue joints are effected inapproximately 6 minutes, when the platensare maintained at a temperatureof 250 to 280 F.

Therefore, it will be evident that, during processing, the platen pressprovides heat and pressure for curing the adhesive thus bonding theparts into an integral structure, and the internally applied pressureforces the facing members if into perfectly flat engagement with thefaces of the platens and retains them in this condition throughout thebonding operation. .Thus, the facing members I! are retained perfectlyflat and the. relatively-soft grid I6 is protected against the otherwiseinjurious effects of the 100 1b. pressure applied by the platen pressalone.

Having thus described my invention, I claim:

1. The method of making a hollow structural unit having two facingmembers of relatively thin material and a core structure between thefacing members composed of a frame of relatively hard material andspacer members of relatively soft material disposed within the framewhich comprises; assembling the facing members and the core structure asaforesaid with an adhesive interposed between the abutting facesthereof; applying a relatively high pressure to the external face ofeach facing member, and substantially simultaneously therewith applyinga'lower pressure to the internal face of each facing member to opposethe relatively higher pressure applied to the external faces of thefacing members.

2. The method of making a hollow structural unit having two facingmembers of relatively thin material and a core structure between the.

facin members composed of a frame of relatively hard material and anelement of relatively soft material disposed within the frame forspacing the said facing members which comprises; assembling the facingmembers and the core structure as aforesaid with an adhesive between theabutting faces thereof applying pressure to the external face of eachfacing memher, and substantially simultaneously therewith applyingpressure fluid into the interior of the hollow unit having a pressurelower than that applied to the facing members, to oppose the higherpressure applied to the external faces of the facing members; andheating the structural unit while maintaining the pressures as aforesaidto bond the aforesaid abutting faces by the adhesive interposedtherebetween.

3. The method of making a hollow structural substantially simultaneouslytherewith applying pressure fluid into the interior of the hollow unitat approximately 80 lbs. per squareinch toopposethepressureappliedtotheexternalfsces of the facing members.

4. The method of makin a hollow panel having two facing lamina ofrelatively thin material and a core structure between the facing laminacomposed of a perimetrical frame of relatively hard material and spacermembers within the frame of relatively soft material, which comprises;assembling the facing lamina and the core structure as aforesaid with anadhesive interposed between the abutting faces of the core and facinglamina; applying heat and pressure to the external face of each facinglamina sumcient to effect bonding of the aforesaid abutting faces, and,simultaneously therewith, applying pressure fluid into the interior ofthe hollow panel at a pressure less than that applied to the externalfaces of the lamina but sufllcient to prevent collapse of the spacermembers of the core structure.

5. The method of making a hollow structural unit having two facingmembers of relatively thin material and a core structure between thefacing members composed of intercrossed strips of relatively softmaterial and a frame of relatively hard material surrounding the edgesthereof, which comprises; assembling the facing members and the corestructure as aforesaid with anadhesive interposed between the abuttingfaces thereof; applying heat at approximately 250 to 280 F. and pressureat approximately 100 lbs. per square inch to the external faces of thefacing members, and, simultaneously therewith, applying pressure fluidinto the hollow spaces between the facing members formed by theintercrossed strips and frame at approximately lbs. P r square inch.

6. The method of making a hollow. panel having two facing lamina ofrelatively thin material and a core structure between the facing laminacomposed of a perimetrical frame of relatively hard material and spacermembers within the frame of relatively soft material, which comprises:assembling the facing lamina and the core structure as aforesaid with anadhesive interposed between the abutting faces of the core and facinglamina; applying heat and pressure to the external face of each facinglamina, and, simultaneously therewith, applying pressure fluid into theinterior of the hollow panel at a pressure less than that applied to theexternal faces of the facing lamina.

7. The method of making a hollow panel having two facing members ofrelatively thin material and a core structure between the facing memberscomposed of a perimetrical frame of relatively hard material and anelement of relatively soft material within the frame for spacing thesaid facing members, which comprises; assembling the facing members andthe core structure as aforesaid with an adhesive interposed between theabutting faces thereof; clamping the internal faces of the facingmembers to the abutting faces of-the core structure under pressure toeffect bonding therebetween. and. substantially simultaneouslytherewith, applying pressure fluid into the interior of the hollow panelat a pressure less than the aforesaid bonding pressure but sufficient toprevent collapse of the spacer elements of thecore structure.

OLIVER CLARENCE DAVIS.

